Effects Of Chemical Insecticides Research Articles

Efficacy of metarhizium anisopliae and beauveria bassiana as biological control agents of African Rice Gall Midge (AfRGM), Orseolia oryzivora Harris & Gagné

African rice gall midge (AfRGM), Orseolia oryzivora (Diptera: Cecidomyiidae) is a significant pest of rainfed and lowland rice that causes about 25% to 100% yield loss. The effectiveness of chemical insecticides has been compromised due to insecticide resistance and concerns over their environmental impact, which necessitated an alternative approach that is safe and more sustainable. The study aimed to determine the effectiveness of Entomopathogenic fungi (EPF), Metarhizium anisopliae and Beauveria bassiana in controlling AfRGM on four popular rice cultivars under screenhouse conditions at AfricaRice/IITA, Ibadan, Nigeria. The experiment was laid out in a 4 x 3 factorial fitted in a completely randomized design (CRD) in three replications. Results showed that although both fungi significantly reduced AfRGM tiller infestation, the degree of reduction varied with the specific fungus and rice variety grown. Beauveria bassiana exhibited better control of AfRGM on FARO 37 and FARO 44 varieties, while M. anisopliae was more effective on FARO 66 and FARO 67 varieties. Tiller infestation had a significant negative correlation with grain yield (r= − 0.87, R2 = 77). The study also indicated that the two fungi strains had no harmful effect on the chlorophyll content and positively influenced agronomic traits and grain yield.

In Vitro Effectiveness of Beauveria bassiana as a Control Agent against Invasive Fall Armyworm (Spodoptera frugiperda) Larvae

Fall armyworm or Spodoptera frugiperda is one of the main pests of corn. It can caused up to 28.08% yield loss. Pest control efforts with broad-spectrum insecticides can cause negative impacts that disrupt ecosystems, non-target biotic factors and the surrounding environment. Beauveria bassiana is an alternative biological control agent that is target-specific. This study was conducted to determine toxic and antifeedant activities of B. bassiana application on third to fifth-instar S. frugiperda larvae. B. bassiana isolates were propagated using corn flakes media and resulted in colonies with conidia density of 1.1×108conidia.g-1. This study used a completely randomized design with 5 treatments and 5 replications. Treatments consisted of P1 namely B. bassiana propagation with a concentration of 60 g.L-1, P2 = 70 g.L-1, and P3 = 80 g.L-1. P0 was a negative control (untreated with B. bassiana) and P4 was a positive control (diazinon with concentrations of 2 ml.L-1). The variables observed were mortality and weight of the leftover feed. The results showed that the formulation of B. bassiana with concentrations of 80 g.L-1 was able to infect armyworms with a mortality percentage of 53.5% which was statistically similar as the effect of chemical insecticides. In addition, inhibition of feeding activity due to treatment could prevent leaf damage up to 68.21%.

Ethnobotanical survey of plants locally used in the control of termite pests among rural communities in northern Uganda

BackgroundTermites are the most destructive pests in many agricultural and forest plantations in Uganda. Current control of termites mostly relies on chemical pesticides. However, the adverse effects of chemical insecticides necessitate the need to search for and popularize the usage of environmentally safer options. Plants represent one of the most accessible resources available for termite control by communities in Uganda. However, limited documented information exists for their contribution in the management of except through verbal sharing. This study aimed at assessing the communities’ knowledge about plants traditionally used in controlling termites among selected communities in Apac District, northern Uganda.MethodAn ethnobotanical survey was conducted between November 2016 and February 2017 in 12 randomly selected villages in the sub counties of Apac and Ibuje of Apac District, northern Uganda. Open-ended questionnaire interviews were used to gather ethnobotanical and sociodemographic data. A total of 381 indigenous people were interviewed [male, 281 (73.8); female, 100 (26.2)]. Data were analysed using descriptive statistics and Informant Consensus Factor (ICF), and the relative frequency of citation (RFC) was determined.ResultsOverall, 70.9% of the respondents were knowledgeable about plants used for control of termites. There was a significant association between respondents’ knowledge of pesticidal plants with age and gender but not with education status. A total of 11 plant species belonging to eight families were identified to be in use for control of termites in Apac. Solanaceae, Eurphorbiaceae and Asteraceae were the most represented families with two species each, while the rest of the families had only one species mentioned. According to the relative frequency of citation (RFC), Kigelia africana (Lam.) Benth. (RFC = 0.43), Vernonia amygdalina Delile (0.18) and Tithonia diversifolia (Hemsl.) A. Gray (0.10) were the most used in the control of termites in the study area. Fruits (45.9%) and leaves (29.2%) were the most used plant parts. Squeezing, crushing and chopping of the plant materials were the most popular methods of preparation and water extract was the commonest mode of formulation of plant parts.ConclusionsThe study has shown that rural populations of the targeted localities possess indigenous knowledge on anti-termitid plants. However, screening is urgently needed to validate their bioactivity and to determine the bioactive constituents responsible for killing the invertebrates in pest management. Furthermore, simple methods for local propagation and cultivation are needed to ensure a sustainable supply of termicidal plant biomass.

The effect of chemical insecticides on the scavenging performance of Steinernema carpocapsae: Direct effects and exposure to insects killed by chemical insecticides

Entomopathogenic nematodes are used widely in biological insect control. Entomopathogenic nematodes can infect live insects as well as dead insects (i.e., they can act as scavengers). It is important to determine compatibility of entomopathogenic nematodes with other pest management tactics such as chemical insecticides. We hypothesized that chemical insecticides have negative impact on scavenging nematodes. According to our hypothesis, we first investigated the effects of direct exposure of Steinernema carpocapsae infectivity juveniles (IJs) to three chemical insecticides, cypermethrin, spinosad or diflubenzuron in terms of nematode survival and virulence. Subsequently, using the same chemicals, we tested the effects of insecticide-killed insects on scavenger nematode penetration efficiency, time of emergence and the number of nematode progeny. Prior to our study, the impact of pesticides on scavenger nematode fitness had not been studied. Fall webworm, Hyphantria cunea, and greater wax moth, Galleria mellonella, larvae were used as host insects. The survival rate of IJs after direct exposure was 83% for cypermethrin and 93–97% for the other insecticides and control. There were no significant differences in the survival and virulence of the nematodes after 24 h exposure to insecticides. The number of nematodes that invaded the insecticide-killed host was significantly higher in cypermethrin and spinosad treated groups and live H. cunea than in the diflubenzoron treated group and freeze-killed control. However, no significant differences were observed in time of emergence. Significantly more progeny IJs emerged from Spinosad-killed insects than the freeze-killed control. In conclusion, we discovered that the fitness of scavenging IJs is not diminished by insecticides in insect cadavers. In fact, in some cases the exposure to chemical insecticides may enhance virulence.

Nanochitin whisker enhances insecticidal activity of chemical pesticide for pest insect control and toxicity

BackgroundNanomaterials in plant protection promise many benefits over conventional pesticide products. Nano-enabled pesticides may alter the functionality or risk profile of active ingredients. Cationic nanochitin whiskers (NC) possess strong biological activity against wheat aphids. However, toxicity and synergistic effects of NC with chemical pesticides against pest insects has not been systemically reported. This study investigated the insecticidal enhancement by NC with Omethoate (40% EC), Imidacloprid (10% WP), and Acetamiprid (40% WG) for pest control using wheat aphid as piercing-sucking mouthparts insect. Fluorescein isothiocyanate labelled NC was used to monitor the uptake and transportation pathway of NC inside the target insects. Toxicity of NC was tested with Sprague-Dawley (SD) rat. Our findings provide a theoretical basis for future application of NC in plant protection against pest insects.ResultsNCs synthesized by acidic hydrolysis were rod-like nanoparticles in a range of 50–150 nm in length and 30–50 nm in width, which examined by electron microscopy and dynamic light scattering methods. The charge density and zeta potential were about 63 mmol/kg and + 36.4 mV, respectively. By absorption and/or contact action of 30–50 mg/L of NC suspension, the corrected mortality of wheat aphids reached up to 80% or above after 12 h treatment, NC could be distributed through digestive system and relocated from mouth to other tissues inside the insect body. When associated with dilutions of conventional pesticides, the corrected mortality were significantly increased up to 95% or above. The dosage of the chemical pesticide and nanochitin in the mixtures (1:1 by volume) were all reduced to half. The acute oral toxicity Lethal Dose 50% (LD50) to SD rat is greater than 5000 mg/kg BW (body weight) in male and female, acute dermal toxicity LD50 is greater than 2000 mg/kg BW of NC.ConclusionsNC has a strong promotive effect on insecticidal effectiveness of chemical insecticides. It was easily absorbed by plant, transported and distributed from mouth to other tissues of the insects while sucking plant fluid. Low acute oral and dermal toxicity to SD rat indicated that it is safe to apply in agriculture and food industry. NCs has a great potential for water-based nanopesticide formulation to reduce chemical pesticide use for future agro-environmental sustainability.

Effects of Chemical Insecticide Imidacloprid on the Release of C6 Green Leaf Volatiles in Tea Plants (Camellia sinensis)

Chemical insecticides are widely used for pest control worldwide. However, the impact of insecticides on indirect plant defense is seldom reported. Here, using tea plants and the pesticide imidacloprid, effects of chemical insecticides on C6-green leaf volatiles (GLVs) anabolism and release were investigated first time. Compared with the non-treated control plants, the treatment of imidacloprid resulted in the lower release amount of key GLVs: (Z)-3-hexenal, n-hexenal, (Z)-3-hexene-1-ol and (Z)-3-Hexenyl acetate. The qPCR analysis revealed a slight higher transcript level of the CsLOX3 gene but a significantly lower transcript level of CsHPL gene. Our results suggest that imidacloprid treatment can have a negative effect on the emission of GLVs due to suppressing the critical GLVs synthesis-related gene, consequently affecting plant indirect defense.

Effect of Chemical Insecticides on the Arthropod Diversity in the Agroecosystem of Red Onion Crops

Effect of Chemical Insecticides on the Arthropod Diversity in the Agroecosystem of Red Onion Crops

Systematic Review of the Effects of Chemical Insecticides on Four Common Butterfly Families

Safeguarding crop productivity by protecting crops from pest attacks entails the wide use of plant protection products that provide a quick, easy and cheap solution. The objective of this study is to understand the effects of insecticides used in agriculture on non-target butterflies, specifically on the families Lycaenidae, Nymphalidae, Hesperiidae and Papilionidae. To achieve this goal, a formal systematic review was performed according to European Food Safety Authority (EFSA) guidelines, by entering a combination of keywords on 3 online databases. Three reviewers independently extracted information on study characteristics and quality. The main results were collected and grouped by the insecticide used, butterflies species and family, and endpoints. The output was valuable but heterogeneous as the endpoints and methodologies of the studies reviewed were different. Few experimental studies on the effects of insecticides on the most common butterfly families have been published. Naled and permethrin are the most commonly used insecticides in the experiments, whilst the target organisms of these studies are Vanessa cardui, Danaus plexippus, Heliconius charitonius, belonging to the Nymphalidae family, and Eumaeus atala, belonging to the Lycaenidae family; the effects were evaluated on all developmental stages, with special attention to the larval phase. This systematic review highlights the need for more studies on the effects of chemical insecticides on non-target Lepidoptera in light of their ecological importance and the extensive use of these chemical products.

English

A plant of genus gaggassa belongs to the family of Ericaceae, and has been widely employed by the traditional healers to treat cockroach pest. The objective of this study was to do preliminary phytochemical screening and insecticidal activity of extracted gaggassa (Agarista salicifolia) plant leaves against cockroach. About 10 g of air dried powdered material of leaves was extracted with 90% ethanol, acetone and water using an electric shaker for 24 h. Thereafter, the extract material was concentrated to dryness under reduced pressure and controlled temperature (50°C) using rotary evaporator. Different leaf extract concentrations of 25, 50, 75 and 100%, respectively were implemented in triplicate experiment and mortality was assessed after 4, 8 and 12 h of treatment time interval. The toxicity test extract of plant was carried out by using adult cockroach, and obtained result showed extracts of LC50 of 1.44 mg/mL from water extract and 1.33 mg/mL from ethanol respectively. No mortality was observed in control treatment. Preliminary phytochemical analysis showed the presence of alkaloids, terpenoids, flavonoids, steroids, tannins and cardiac glycosides. Finally, the high polyphenolic and flavonoid contents of the plants suggest their potential source of botanical insecticides. Overall results suggest that extracts from gaggassa plant leaves showed the highest insecticidal effects on cockroach. Considering the side effect of chemical insecticides to human health, it is suggested that the use of organic insecticides should be encouraged so as to ameliorate health problems, since it is eco-friendly in nature. The plants are good candidates to be developed as sources of natural insecticides for the pest management. Key words: Bioactive compounds, ethanolic extracts, total phenolic content and toxicity.

Industrial Production of Bacillus Thuringiensis Based Bio-Insecticide: Which Way Forward?

Considering long term negative effect of chemical insecticides on the environment and human health, globally biological pest management has been promoted. Bacillus thuringiensis (Bt) is mostly explored and commercially successful microbial insecticide. According to a report, it constitutes almost 2% of insecticide market [1]. There are at least 32 companies involved in Bt based bio-insecticide business [2]. Microbiologically, Bt is gram-positive, facultative anaerobic bacterium most common habitats of which are soil, water or plant surfaces [3]. It can produce almost nine distinct types of toxins, among them δendotoxin, which is toxic to a range of insects, is mostly studied for insecticidal application [3]. This type of toxin is also known as Cry protein or Cry toxin and belongs to a family of toxin called pore forming toxins. They can kill the larvae of different insect groups usually by forming pore in mid-gut cell membrane followed by celllysis [1]. There are at least 500 known cry gene sequences which are broadly divided into 67 groups named as Cry1 to Cry67 [1]. Expression of the genes encoding Cry toxin are controlled by certain RNA polymerase which is produced during sporulation. Cry toxin production, therefore, coincides with spore formation [2], and hence, achieving high spore count is one of the major targets of Bt fermentation.

Genotoxic effects of two different classes of insecticide in developing chick embryos

Pesticides provide considerable protection against pest population; however, rampant accumulation of these chemicals into varied habitats across the globe necessitates the need for a careful screening of each chemical due to toxic manifestations. In the current study, the genotoxic potential of two different classes of commercial insecticides – chlorpyrifos and cypermethrin combination and Spinosad, a naturalyte were compared. Rhode Island Red chick embryos were exposed to different doses of either of these insecticides individually, by in ovo treatment. Genotoxicity was then evaluated through micronucleus (MN) test and Comet assay. The combination insecticide exposure at low doses of 0.05 and 0.1 μg/egg induced DNA damage as evidenced by an increased tail moment in the Comet assay. Further, the presence of micronucleated erythrocytes and also various abnormal cells including dacryocytes, microcytes, erythroplastids, squashed/notched nuclei, and spindle-shaped erythrocytes in the blood smear consolidates indicate the presence of insecticide-induced genotoxicity. Spinosad, however, was found only mildly genotoxic but at a high dose of 1.5 mg/egg. The results indicate that usage of naturalyte insecticide may be a better option to minimize the harmful effects of chemical insecticides.

The effect of different pesticides on reproduction of entomopathogenic nematodes

Entomopathogenic nematodes (EPNs) in the families Steinernematidae and Heterorhabditidae are generally considered beneficial nematodes. These beneficial nematodes can serve in integrated pest management (IPM) in agro-ecosystems. The effect of chemical insecticides (11 different pesticides) on Steinernema sp. (EBN-1e), and Heterorhabditis bacteriophora (EBN-10k) was determined under laboratory conditions. Generally, EBN-1e Steinernema strain was more tolerant to different tested insecticides than Heterorhabditis strain. The survival of IJs was more than 90% after treatement with Captan, Methomyl, Mancozeb, Benomyl, Trimiltox forte and Diafenthiuron, for EBN-1e nematode strain, while Chlorfluazuron decreased its survival to less than 5%. In contrast, the survival of Heterorahbditis strain was less than the Steinernema strain. There were significant differences in reproduction rates between EBN-1e and EBN-10k exposed to different chemical insecticides. The EBN-1e strain had higher reproduction rate than EBN-10k in all treatments. In general, there was significant difference in reproductive rates between the species concentrations (500 IJs and 1000 IJs) exposed to different chemicals or between exposure times (48 h. and 96 h.)

CHARACTERISTICS OF ARTHROPOD COMMUNITY AND THEIR DIVERSITY RESTORATION IN LEAFY VEGETABLE FIELDS

Abstract The effect of chemical insecticides on the structure and diversity of arthropod communities in various vegetable fields and the restoration of their biodiversity after stopping application of chemical insecticides were studied. The results showed that the effect of chemical insecticides on the arthropods in vegetable fields could be characterized the species structure, the diversity index and the evenness of species distribution. Components of arthpod species depended closely on the species number of insect pests, predatory natural enemies and spiders. Investigations showed that the numbers of species in the vegetable fields managed with chemical insecticides were obviously reduced, and their diversity indices were lower comparing with that without chemical insecticides. When the applications of chemical insecticides were stopped in vegetable fields, the index of population trend (I) of dominant insect pests decreased greatly, the control effect of natural enemies on major insect pests increased, and the diversity index of arthropod increased at the same time. Thus, limiting the application of chemical insecticides, resuming the environment of vegetable fields destroyed by using chemical insecticides, escalating the control ability of natural enemies on main insect pests will play an important role in the ecological control of insect pests in vegetable fields.

Use of Chemical and Microbial Insecticides Against Pests of Common Beans

Effects of chemical insecticides and a microbial insecticide on insect pests in relation to yield of common beans, Phaseolus vulgaris L., were investigated. Two preflowering applications of lindane or carbaryl, two postflowering applications of Bacillus thuringiensis Berliner ( Bt ), and a spray of lindane or carbaryl effectively controlled bean pests. Lindane or carbaryl applications controlled preflowering pests and flowerthrips, Taeniothrips sjostedti Trybom. Two applications of Bt during the postflowering growth stage of bean plants controlled the larvae of pod borers, Maruca testulalis (Geyer) and Heliothis armigera (Hubner) as effectively as two applications of lindane or carbaryl over the same period. Two applications of lindane during the prellowering and the late pod stages combined with two applications of Bt gave high seed yields of 1,308 and 1,307 kg/ha for 1982 and 1983 trials, respectively. Thus, Bt is as effective as chemical insecticides in controlling pod borers. Integrated use of chemical and biological insecticides could be used for controlling bean pests.

The effects of chemical insecticides and insecticidal adjuvants of a Heliothis nuclear-polyhedrosis virus

Of 12 insecticides or insecticidal adjuvants tested (endrin, DDT, methylparathion, toxaphene, toxaphene-DDT, carbaryl, Triton B-1956, Triton X-100, Triton X-152, Triton X-172, Multifilm Buffer-X, xylene, and carbonated water), only methylparathion adversely affected the infectivity associated with polyhedral inclusion bodies of the nuclear polyhedrosis of Heliothis spp. A 30% reduction in larval mortality was also detected in carbonated water-virus mixtures, but this reduction was not statistically significant at the 5% level.